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Stocks and Shares ISA Calculator
Project tax-free growth on a UK Stocks & Shares ISA and compare against a taxable General Investment Account. Compounded monthly. Based on 2026/27 allowances.
Your inputs
Your tax band (for GIA comparison)Dividend tax above £500 allowance · CGT above £3,000 allowance.
Projected ISA value after 20 years
£152,067
Tax-free
Total contributed
£77,000
opening balance + monthly deposits
Tax-free growth
£75,067
compounded monthly at 6%
Stocks & Shares ISA vs taxable GIA (higher rate)
S&S ISA (tax-free)
£152,067
Growth: £75,067
GIA (after tax)
£134,086
Net growth: £57,086
Illustrative tax saved with the ISA wrapper+£17,981
Estimated dividend tax + CGT on the GIA over 20 years: £17,981. Assumes the dividend allowance (£500) and CGT allowance (£3,000) stay at 2026/27 levels.
Educational information only — not regulated financial advice. Figures are illustrative and assume the return rate stays constant. Real investment returns vary year to year and can be negative. Past performance is not a guarantee of future returns.
Common Stocks & Shares ISA questions
How much can I put in a Stocks and Shares ISA in 2026/27?
The total annual ISA allowance is £20,000 across all ISA types. You can put all of it into a S&S ISA, or split it across Cash, Innovative Finance and Lifetime ISAs.
Are gains in a Stocks and Shares ISA tax-free?
Yes — growth, dividends and capital gains inside a S&S ISA are free of UK income tax, dividend tax and CGT, regardless of how much you gain.
Can I have a Cash ISA and a S&S ISA in the same year?
Yes. Since April 2024 you can pay into multiple ISA types in the same tax year, provided the total stays within £20,000.
What return should I model?
Long-run global equity returns have averaged around 5–7% real (after inflation). Try a few scenarios to see how outcomes change. Past performance is not a guarantee.